Location-corrector for removing sun-induced effects in the global positioning system

Abstract

The system for location-correction for removing the sun-induced effects in the global positioning system (GPS) caused by the problem of transforming the frequency of coherent radio signals to the geocentric inertial coordinate frame involves an implicit, dependence on earth-sun-clock orientation. This is accomplished by determining the systematic errors associated with sun-induced effects that alter the frequency of the transmission of every satellite within the GPS because of the GPS satellites orbit around both the sun and the earth and applying a correction factor to the initially determined position to obtain the true position within 10 cm to one meter.

What is claimed is: 
     
       1. A device for determining the position of a global positioning system (GPS) receiving station comprised of: a plurality GPS satellites, each satellite transmitting a plurality of electromagnetic signals containing the satellite ephemeris data and ionospheric correction information;   a receiver for receiving the plurality of electromagnetic signals of a first plurality of standard GPS satellite frequencies from the plurality of GPS satellites;   means for determining a first terrestrial position of the receiver from the GPS satellites ephemeris data and ionospheric correction information based on the plurality of standard GPS frequencies and reading and deciphering both the C/A and P codes;   means for determining a velocity and position of the earth in relation to the sun and a rotational velocity of the receiver about the center of the earth at the position of the receiver;   means for determining a position and velocity of each GPS satellite relative to the center of the earth from the ephemeris data;   means for calculating a non-path-dependent second order Doppler frequency shift contribution (O 1 →2 2 ) and path-dependent second order Doppler frequency shift contribution (N 1 →2 2 ) in the transmission from each satellite and the change in frequency of transmission of the satellites from the plurality of standard GPS satellite frequencies resulting from sun-induced effects;   means for applying the calculated change in frequency of each GPS satellite to the first standard GPS frequency received by the receiving station to correct the first terrestrial position of the receiver; and   means for displaying the corrected position of the receiving station.   
     
     
       2. A device, as shown in claim 1, wherein the means for determining a first terrestrial position of the receiver from the GPS satellites ephemeris data and ionospheric correction information based on the plurality of standard GPS frequencies; means for determining a velocity and position of the earth in relation to the sun and a rotational velocity of the receiver about the center of the earth at the position of the receiver; means for determining a position and velocity of each GPS satellite relative to the center of the earth from the ephemeris data; means for calculating a non-path-dependent second order Doppler frequency shift contribution (N 1 →2 2 ) and path-dependent second order Doppler frequency shift contribution (O 1 →2 2 ) in the transmission from each satellite and the change in frequency of transmission of the satellites from the standard GPS satellite frequency resulting from sun-induced effects; means for applying the calculated change in frequency of each GPS satellite to the first standard GPS frequency received by the receiving station to correct the first terrestrial position of the receiver; and means for displaying the corrected position of the receiving station is a computer. 
     
     
       3. A device, as shown in claim 1, wherein the means for determining a first terrestrial position of the receiver from the GPS satellites ephemeris data and ionospheric correction information based on the plurality of standard GPS frequencies; means for determining a velocity and position of the earth in relation to the sun and a rotational velocity of the receiver about the center of the earth at the position of the receiver; means for determining a position and velocity of each GPS satellite relative to the center of the earth from the ephemeris data; means for calculating a non-path-dependent second order Doppler frequency shift contribution (N 1 →2 2 ) and path-dependent second order Doppler frequency shift contribution (O 1 →2 2 ) in the transmission from each satellite and the change in frequency of transmission of the satellites from the standard GPS satellite frequency resulting from sun-induced effects; and means for applying the calculated change in frequency of each GPS satellite to the first standard GPS frequency received by the receiving station to correct the first terrestrial position of the receiver are a plurality of electronic circuits. 
     
     
       4. A device, as shown in claim 1, wherein the means for determining a first terrestrial position is a plurality of electronic circuits. 
     
     
       5. A device, as shown in claim 1, wherein the means for determining a first terrestrial position is a computer. 
     
     
       6. A device, as shown in claim 1, wherein the means for determining a velocity and position of the earth in relation to the sun and a rotational velocity of the receiver about the center of the earth at the position of the receiver is a plurality of electronic circuits. 
     
     
       7. A device, as shown in claim 1, wherein the means for determining a velocity and position of the earth in relation to the sun and a rotational velocity of the receiver about the center of the earth at the position of the receiver is a computer. 
     
     
       8. A device, as shown in claim 1, wherein the means for determining a position and velocity of each GPS satellite relative to the center of the earth is a plurality of electronic circuits. 
     
     
       9. A device, as shown in claim 1, wherein the means for determining a position and velocity of each GPS satellite relative to the center of the earth is a computer. 
     
     
       10. A device, as shown in claim 1, wherein the means for calculating a non-path-dependent and path-dependent second order Doppler frequency shift contribution in the transmission of each satellite and the change in frequency of transmission of the satellites from the standard frequency that results from sun-induced effects is a plurality of electronic circuits. 
     
     
       11. A device, as shown in claim 1, wherein the means for calculating a non-path-dependent and path-dependent second order Doppler frequency shift contribution in the transmission of each satellite and the change in frequency of transmission of the satellites from the standard frequency that results from sun-induced effects is a computer. 
     
     
       12. A device, as shown in claim 1, wherein the means for applying a resulting change in frequency of each GPS satellite to the first standard GPS frequency received by the receiving station is a plurality of electronic circuits. 
     
     
       13. A device, as shown in claim 1, wherein the means for applying a resulting change in frequency of each GPS satellite to the first standard GPS frequency received by the receiving station is a computer. 
     
     
       14. A device, as shown in claim 1, wherein the means for displaying the corrected position of the receiving station is a computer. 
     
     
       15. A device, as shown in claim 1, wherein the means for displaying the corrected position of the receiving station is a video display. 
     
     
       16. A method for improving the determined position of a receiver utilizing global positioning system (GPS) satellites comprising the steps of: determining a first terrestrial position of the receiver from the GPS satellites ephemeris data and ionospheric correction information based on a standard GPS frequency;   determining a velocity and position of the earth in relation to the sun and a rotational velocity of the receiver about the center of the earth at the position of the receiver;   determining a position and velocity of each GPS satellite relative to the center of the earth from the ephemeris data;   calculating a second order Doppler frequency shift contribution in the transmission from each satellite and the change in frequency of transmission of the satellites from the standard GPS satellite frequency resulting from sun-induced effects;   applying the calculated change in frequency of each GPS satellite to the first standard GPS frequency received by the receiving station to correct the first terrestrial position of the receiver; and   displaying the corrected position of the receiving station.   
     
     
       17. A method for improving the determination of Kalman estimators of control segment for global positioning system (GPS) satellite position, satellite clock bias, frequency offset and drift rate, and satellite solar pressure constants for each GPS satellite comprising the steps of: determining a first estimate of a first GPS satellite frequency at each receiving station employed in the control segment, based on a change in satellite frequency at each receiving station utilizing a known position of each receiving station to determine a sun-induced correction in a received signal to improve accuracy of a deviation of GPS time relative to an atomic standard time at each receiving station;   determining a second estimate of the clock bias, frequency offset and drift for each GPS satellite at each receiving station to obtain a second frequency measurement; and   inputting the second estimate from the second frequency measurement of clock bias, frequency offset and drift to determine Kalman estimators of GPS satellite position, satellite velocity, solar pressure constants, and the satellite clock bias, frequency, offset, and drift rate.